Canine aggression is defined as threatening or harmful behavior directed toward another individual, including dog on dog aggression, aggression toward people, and aggression toward other animals.
Aggression can include threat displays, lunging, growling, snarling, snapping, and biting. In animals, aggressive behaviors are a means for communication. Dogs use aggressive displays, threats, and attacks to resolve competitive disputes over resources (esp. territory, food), to increase their reproductive potential, or to escape threatening situations. “Aggression” describes the behavior, but does not give any information about underlying motives or causes – it does not always explain why the dog is being aggressive. In fact, aggression can have multiple motivations.
How is Canine Aggression Classified?
Aggression can be subdivided into types of aggression, based on intended target, body postures taken by the dog during the aggression, and the dog’s health. There are other factors to consider as well, such as the resource the dog may want, the estrus (heat/ovulation of females) status of animals involved, and the location of the aggressive encounter.
In determining the classification, the factors surrounding the initial aggressive event are important to take into consideration, since over time the effects of learning (consequences) - including the reactions of the owner and the resulting stimulus (e.g., whether and how the targeted person or animal retaliates or retreats) - will affect how further aggression is displayed.
Ethologists, persons who study animal behavior, use the term “agonistic” to refer to the behavior of animals (usually of the same species) that involves conflict or combat. These encounters can involve fighting, escape, dominant and submissive gestures, and posturing.
Aggressive behavior can also be divided into offensive (going after the other individual) and defensive (defending oneself from a perceived threat) aggression. In dogs and cats the function of the aggression is most commonly used as the basis of classification. Common diagnostic categories used in veterinary behavioral medicine are:
- Dominance related
- Conflict aggression
- Possessive, protective and territorial
- Intermale and interfemale
- Pathophysiologic (medical)
Aggression can also be classified by the target of the aggression, whether aggression toward familiar people, aggression toward unfamiliar people, aggression toward familiar animals, aggression toward unfamiliar animals.
Note that there is no one single cause of aggression. In addition, an individual pet can display one or more forms of aggression and that multiple factors and stimuli may combine to push the dog to a point where aggression is displayed. For example, a dog may be fearful and exhibit territorial behaviors toward children. This dog may only exhibit aggression if a strange child comes onto the dog’s property while the dog is tied up, making the dog feel cornered without a means for escape. When the dog learns that snapping and growling are successful at chasing the child away, the dog may begin to generalize its aggression toward similar stimuli (e.g., other children) and similar situations (petting, hugging).
Is Canine Aggression Normal?
It is estimated that from two to five million human bite wounds occur annually across North America. So while aggressive behaviors may be “normal,” when they result in human or animal injury, the behavior is dangerous and unacceptable. Human safety must always be the primary consideration when discussing aggression. Most people are bitten by animals they own or that are known to them. It is therefore important to be able to identify aggressive dogs so as to prevent injuries wherever possible.
Some aggression in dogs may have abnormal components, such as when the dog is excessively anxious or unable to control the initiation, termination, or intensity of the interactions with others. These problems may arise from genetics, lack of sufficient socialization, insufficient maternal care, or excessively fearful events that have occurred, particularly during the development stages. However, even though health problems and degenerative changes may be present, they may or may not contribute to the aggressive behavior.